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Heart Failure

What Is Heart Failure?

Last modified: 
16/04/2013 - 13:09

Contributing Author: Guy Slowik FRCS

Heart failure does not mean that the heart has failed. It simply means that the heart does not pump as powerfully as it used to, and is not working efficiently enough to meet the body's needs for oxygen-rich blood.

In heart failure:

  • The contractions of the heart muscle are less powerful than they used to be.
  • Less blood is pumped out from the heart with each beat.
  • The pumping heart chambers overfill with blood, because the heart muscle is not strong enough to pump out all the blood it receives.

When the heart can't pump efficiently, a number of things happen.

  • Your circulation slows down. Your muscles don't get all the oxygen they need, which is why you may tire easily. Sometimes blood flow to the brain is reduced, which is why you may feel dizzy or faint.
  • Blood backs up in the veins, and fluid seeps from the veins into the surrounding tissues. That causes swelling (edema). This is most common in the legs and ankles, but may affect other parts of the body as well.
  • Blood also backs up in the blood vessels within the lungs. The inside of the lungs becomes swollen and stiff with the extra fluid, which is why you may feel short of breath and may have a cough.

There is another problem: extra fluid in the blood. When the blood flow around the body slows down, as occurs in heart failure, the brain gets a signal that there is not enough blood to go around. To make up for the decreased blood flow, the brain signals to the kidneys to retain fluid in the blood. This has further effects:

  • In the daytime, this extra fluid in the blood adds to the swelling in legs and ankles.
  • When you are lying down, the fluid may flow to other parts of your body. Some of it gets into the tissue around your lungs, making it especially hard to breathe at night.
  • The kidneys try to get rid of this extra water, which is why you may have to go to the bathroom more often, especially at night.

These effects are responsible for the symptoms of heart failure.

Nice To Know:

Different Types of Heart Failure:

There are 2 major types of heart failure:

  • In the one type, the heart is unable to pump effectively, so less blood is pumped out of the heart with each beat. This is called systolic heart failure (systolic refers to the period in the pumping cycle when the heart pumps and is not resting between pumps).
  • In the other less common type, the heart is unable to relax normally between pumping. This is called diastolic heart failure (diastolic refers to the period in the pumping cycle when the heart rests between beats).

Other terms used to describe various types of heart failure include:

Congestive heart failure - A general term used to describe heart failure. Refers to the fluid in the lungs or body that results from the heart's inability to pump. Actually, this is only one aspect of heart failure, and does not always occur.

Right-sided heart failure - Results from failure of the pumping action of the right side of the heart and causes swelling in the body, usually the legs and abdomen.

Left-sided heart failure - Results from failure of the pumping action of the left side of the heart and causes congestion in the lungs.

Forward heart failure - Is the inability of the heart to pump enough blood to meet the needs of the body for oxygen during exercise or at rest.

Backward heart failure - Is the inability of the heart to meet the oxygen needs of the body when heart filling pressures are too high.

High output heart failure -This differs from the usual heart failure in that the heart may pump out its usual amount of blood, but that still may not be enough to meet the body's needs.

This may occur in certain conditions when the body's need for blood is increased (for example hyperthyroidism, or Pagets Disease), and the heart is not able to meet those increased needs for oxygen-rich blood.

For more detailed information about hyperthyroidism, go to Hyperthyroidism.

The Heart As A Pump

The heart has four chambers-two that allow blood to flow into it

and two that pump the blood out to the rest of the body:

The right ventricle pumps blood to the lungs. There, the blood picks up oxygen, then it returns to the left side of the heart.

The left ventricle then pumps the oxygen-rich blood out to the rest of the body.

The heart is a strong, muscular pump, a little larger than a fist. A healthy heart pumps out five to six quarts of blood every minute when we are at rest and up to 20 quarts during exercise.

In heart failure, the heart is unable to pump with the same force it used to, so the ventricles can't keep up with their work. Less blood than usual is pumped out with each beat, usually causing important symptoms.

Facts About Heart Failure

  • In the average lifetime, the human heart beats (expands and contracts) more than 2.5 billion times.
  • Heart failure affects between 2 to 4 million people in the U.S.
  • 300,000 new cases of heart failure diagnosed every year.
  • Many people with heart failure remain undiagnosed because their symptoms-shortness of breath, tiredness, and weakness-are overlooked, ignored, or attributed to aging.
  • The good news is that proper diagnosis and new forms of treatment are enabling people with heart failure to live longer, more active lives.

 

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From Andrew Maynard - Chair of the University of Michigan Department of Environmental Health Sciences, with help from David Faulkner - 2013 Master of Public Health graduate.